Dryer vents are regularly used for directing exhaust air from clothes dryers to the outdoor atmosphere. The outside damper of the regular dryer vent, when operating properly, closes automatically by gravity when the dryer is not in operation for preventing cold air from getting inside the dryer and, eventually, inside the house in the winter. However, the cold barrier formed by the damper is very crude and a substantial amount of cold air penetrates inside the house through the dryer vent. Now that great emphasis is placed on energy saving, it becomes important to cut down heat looses, wherever possible, and this would certainly include the energy loss through clothes dryer vents.